High-value hints should displace low-value ones, not stack on them

What it is

When slots are scarce, a more useful hint should replace the lower-value hint occupying the slot, not stack another layer beside it. Stacking puts two interruptions in front of the user, doubles the dose, and drops reading of both. Displacement admits the channel holds one sentence at a time. This is priority at runtime: the higher one comes up, the lower one yields. It is not another ranking principle, and not new-feature hints waiting after the budget is spent.

Why it happens

Attention needs a gap to recover. Two overlays in close succession eat the gap; strategy flips from reading to clearing the board. Products treat stacking as “everyone got theirs”: a feature hint still up, a launch bar also floating. For teams, both shipped; for the channel, one over-fire. Displacement turns conflict into substitution: a repair for the current-task failure comes up, the launch bar vanishes from this session (not deleted—not shown this time). Substitution also carries information: the displaced item admits it was worth less in this moment, and should be logged as a yield, not as “shown”—logging shown wrongly spends its seen flag or lets operations think reach happened. A covert stack is a dot plus a bottom bar plus a badge on the same screen: not two bubbles, still more dose.

Where it stops holding

Surfaces that truly do not compete for attention (silent copy on a settings page versus a work-area interruption) may coexist; that is not stacking. Error blocks must be able to displace teaching; teaching must not displace errors. Two equally high-value hints at once need a tie-break (the one closer to the current object wins), not both firing. Assistive-tech users can hear one layer at a time; a stack becomes an unescapable speech pile, so displacement is an access requirement, not manners.

Applying it

• Allow at most one automatic interruption per session at a time; on conflict, replace by the existing priority, and do not mark the loser as shown.
• Do not give a defeated hint a second surface (a dot, a bar) as a consolation lap around replacement.
• Log each conflict as a yield in the registry, so persistently losing low-value hints can be retired rather than queued forever.
• Verify by staging “launch bar + current-task repair” both ready: only the repair should appear. Both on screen, or the loser returning as a dot, is stacking.

Related

• Within the group: H2.10.1 Shared hint budgets need a single priority order across teams · H2.10.3 Hint fatigue can be read from ignore and dismiss rates · H2.10.4 When the budget is spent, new-feature hints wait in queue
• Adjacent: H2.07 Hint Restraint · H5.04 Notification bundling · E4.16 Overlay stacking and escape
• Search terms: hint displacement · do not stack overlays · preemption